ESTRO 36 Abstract Book

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S349 ESTRO 36 2017
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Results
RapidPlan DVH analysis of all 54 pt indicated that 4/9
patients with RP had the highest CL doses, and 3 had high
IL doses(figure). 2/3 pt developing LH had the highest
volumes of PBT receiving high doses >40Gy and
Dmax>70Gy. For the 15 pt who developed ≥G3toxicity, the
non-toxicity model showed that 5 of their plans had up to
2.5x higher CL mean dose than predicted, all these pt had
RP. For 3 patients, the clinical plans had higher maximum
PBT doses(70-82Gy) than the model,2 of these pt
developed LH and 1 post-SABR atelectasis. For the other 8
pt, clinical plans were judged to be good.
Conclusion
A RapidPlan model identified the potential for plan
improvements in nearly 50% of pt undergoing SABR for lung
tumors ≥5cm, who developed G≥3 toxicity.Such plan
quality checks are important for this type of higher-risk
treatment. They could also help to improve quality of
clinical studies.
PO-0675 Evaluating commercial delineation software
in routine clinical practice: analyzing time and quality.
T. Lustberg1, W. Van Elmpt1, J. Van der Stoep1, J. Van
Soest1 , M. Gooding2 , A. Dekker1
1 Department of Radiation Oncology MAASTRO- GROW,
School for Oncology and Developmental Biology-
Maastricht University Medical Centre, Maastricht, The
Netherlands
2 Mirada Medical Ltd, Science and Medical Technology,
Oxford, United Kingdom
Purpose or Objective
Delineation of organs at risk (OAR) and target volumes is
vital for treatment planning in radiation oncology. This
process is very time consuming and quality of the
delineation depends on the skill level of the observer.
Automatic delineation software is commercially available
but rarely used in clinical practice. The aim of this study
to evaluate the quality of automatic delineation of OARs
and the time that could potentially be gained by
commissioning automatic delineation software for clinical
use.
Material and Methods
Twenty stage I-III NSCLC patients were selected from
routine clinical practice and their CT scans were used to
delineate OARs. The following OARs were delineated: left
lung, right lung, heart, spinal cord, esophagus,
mediastinum, left brachial plexus, right brachial plexus
and carina. Each OAR was delineated 3 times, once
manually by a technician, once using commercial atlas-
based delineation software and once by adjusting the
software generated delineation to match clinical
guidelines by the same technician. The time needed
perform manual delineation and the adjustments to the
automatically generated delineation were recorded. The
atlas was derived from 10 stage I NSCLC patients collected
from clinical practice. To compare the delineations, the
maximum Hausdorff-distance was computed for each
patient for each OAR in each CT slice between the manual
delineation and the atlas, and between the manual
delineation and the adjusted atlas. The mean of these
maximums was calculated and presented as a boxplot for
each OAR for the two comparisons together with the time
required to perform the delineations.
Results
Delineation of the left lung, heart, esophagus, left and
right brachial plexus and carina was quicker if the
automatically generated delineation only needed minor
adjustments (Figure 1B). The right lung, spinal cord and
mediastinum show a time gain on average, but not for all
cases (Figure 1B). The adjustment of the delineation
created by the automatic delineation software resulted in
a smaller mean maximum Hausdorff-distance for all OARs
compared to the manual delineation (Figure 1A), but there
was still a difference to the manual delineation.
Figure 1: A) Delineation mean maximum Hausdorff-
distance for each OAR. B) Time needed to delineate the
OARs.
Conclusion
Based on the results above, we conclude that
automatically generated delineations save time for the
majority of the cases and after minor adjustment meet
clinical guidelines. Further investigation is needed into
the quality of the automatic delineation software and
inter-observer variability.
PO-0676 outcomes of synchronous and metachronous
pulmonary oligometastasis treated with SBRT
A. Sharma1, M. Duijm1, E. Oomen-de Hoop2, J. Aerts3, C.
Verhoef4, M. Hoogeman1, J. Nuyttens1
1Erasmus MC-Daniel den Hoed Cancer Center-
Rotterdam- The Netherlands, Department of Radiation
Oncology, Rotterdam, The Netherlands
2Erasmus MC-Daniel den Hoed Cancer Center-
Rotterdam- The Netherlands, Department of Medical
Oncology, Rotterdam, The Netherlands
3Erasmus MC-Daniel den Hoed Cancer Center-
Rotterdam- The Netherlands, Department of
Pulmonology, Rotterdam, The Netherlands
4Erasmus MC-Daniel den Hoed Cancer Center-
Rotterdam- The Netherlands, Department of Surgical
Oncology, Rotterdam, The Netherlands
Purpose or Objective
The purpose of our study was to evaluate overall survival
(OS) and identify factors associated with OS in patients
diagnosed with inoperable pulmonary oligometastatic
tumors.
Material and Methods
Between 2005 to 2015, 326 inoperable pulmonary
oligometastasis in 206 patients with ≤ 5 metastasis in no
more than two organs were treated with stereotactic body
radiotherapy (SBRT). Synchronous metastases were
defined as presence of metastases within 5 months of
diagnosis of primary tumor, otherwise they were assigned
to the metachronous group. Risk adapted SBRT was used
to treat peripheral lung metastasis with 51 Gy or 54Gy or
60 Gy in 3 fractions or 30Gy in single fraction, central
tumors received 50 Gy-55Gy in 5 fractions or 60Gy in 8
fractions and metastasis located close to esophagus or in
mediastinum received 6x8 Gy, 7x7Gy or 8x7Gy. Dose to
PTV was prescribed at the 70-90% isodose line (median
78%), covering at least 95% of PTV. OS was calculated from
date of first SBRT session to date of death or date of last
follow up for alive patients. The following variables were
assessed for prognosis: age, gender, primary site,
metachronous versus synchronous tumors, metastatic
burden in body, metastatic burden in lungs, presence of
extra pulmonary metastasis, delivery of pre SBRT
chemotherapy, disease free interval, biological